[blank] mL of 6.0 M H2SO4 are needed to prepare 300 mL of 1.0 M H2SO4 solution.

50

mL x M = mL x M (works for dilution problems but not for all stoichiometry problems.)

To determine the amount of 6.0 M H2SO4 needed to prepare a 300 mL 1.0 M H2SO4 solution, we can use the formula:

C1V1 = C2V2

Where:
C1 = Concentration of the initial solution (6.0 M)
V1 = Volume of the initial solution (unknown)
C2 = Concentration of the final solution (1.0 M)
V2 = Volume of the final solution (300 mL)

We can rearrange the formula to solve for V1:

V1 = (C2 * V2) / C1

Plugging in the values:

V1 = (1.0 M * 300 mL) / 6.0 M
V1 = 50 mL

Therefore, 50 mL of the 6.0 M H2SO4 solution is needed to prepare a 300 mL 1.0 M H2SO4 solution.